[LyX/master] Make all unbreakable spaces of the same Color_latex color

[Daniel]

On 2020-06-23 23:46, Jean-Marc Lasgouttes wrote:
> Le 23/06/2020 à 23:11, Jean-Marc Lasgouttes a écrit :
>> commit 49e1466f93b63b0489549d40ebbde944eff1c7f6
>> Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
>> Date:   Tue Jun 23 23:33:37 2020 +0200
>>
>>      Make all unbreakable spaces of the same Color_latex color
>>      Of course, this means that negative spaces cannot be recognized 
>> anymore.
> 
> I did not mean to commit this yet, but it is a good occasion to discuss 
> the issue of space color. I can revert that if needed.
> 
> I am not sure what was the logic of colors right now.

A wild guess on the logic:

There are two visual dimensions at which spaces are distinguished: color 
(red/blue) and height (high/low)

high/blue: positive (normal) spaces
high/red: negative spaces

It makes sense to me that these spaces fall into one category (high) and 
that positive/negative is distinguished as blue/red.

Then there are two more spaces left:

low/red: protected
low/blue: interword

To distinguish them from the other spaces they are low. To distinguish 
them from each other (and don't introduce new colors) they are red/blue.